Cell electrode plate and process for producing the same

ABSTRACT

A cell electrode plate in which at least one of opposite widthwise ends of longitudinally discontinuous exposed portions with no coatings made of electrode active material on a core member made of metal foil includes pass-by transition portions for press rolls, the transition portions having a thickness substantially the same as that of the coatings. As a result, without complicating a production line, a core member is prevented from being broken and the production line is operated smoothly so as to attain improved productive efficiency and reduced equipment expenses.

TECHNICAL FIELD

The present invention relates to a cell electrode plate and a processfor producing the same, said cell electrode plate comprising a band-likecore member made of metal foil with a plurality of coatings made ofelectrode active material applied longitudinally of and discontinuouslyon at least one of upper and lower surfaces of the core member.

BACKGROUND ART

In production of a cell electrode such as lithium-cell positive polemember, conventionally, electrode mixture or positive pole activematerial such as LiCoO₂ is applied and dried on a core member orcollector made of metal foil such as aluminum or copper foil and then ispressed by a roll press machine with press rolls so as to enhance bulkdensity of the positive pole active material.

The cell electrode plate thus produced by applying and drying theelectrode active material such as positive pole active material on thecore member is shown in FIGS. 1 and 2 in which reference numeral 1denotes a band-like core member or collector made of metal foil such asaluminum foil having substantially uniform width; 2, coatings made ofelectrode active material such as positive pole active material appliedand dried as sheets on upper and/or lower surface of the core member 1.The core member 1 and the coatings 2 provide a cell electrode plate 3.The coatings 2 of uniform size are arranged longitudinally of anddiscontinuously on the core member 1.

Pressing of the cell electrode plate 3 shown in FIGS. 1 and 2 by pressrolls of a roll press machine is shown in FIGS. 3 and 4 in whichreference numeral 4 denotes a roll press machine with a pair of upperand lower press rolls 5 and 6. The cell electrode plate 3 is pressedwhile it is passed through the rolls 5 and 6, the coatings 2 made ofelectrode active material being compressed for improvement of its bulkdensity.

Prior art about application of electrode active material on a coremember made of metal foil is shown, for example, by Reference 1 andprior art about pressing of electrode active material by press rolls ofa roll press machine for improvement of bulk density of the electrodeactive material is shown, for example, by Reference 2.

8 Reference 1] JP 9-274909 A

[Reference 2] JP 11-3701 A

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

However, when the core member 1 made of metal foil and having thecoatings 2 made of electrode active material arranged longitudinally ofand discontinuously on the core member is pressed by the press rolls 5and 6 of the roll press machine 4 for improvement of bulk density of theelectrode active material as shown in FIGS. 3 and 4 and upon passage,through the press rolls 5 and 6, of discontinuous exposed portions 7 ofthe core member 1 where no coatings 2 are provided, the press rolls 5and 6 may fall in the exposed portions 7 to attack the core member 1,disadvantageously resulting in possible breakage of the core member 1and resultant lowering of productive efficiency due to shutdown of theproduction line.

In order to prevent the core member 1 from being broken, low tensionapplicators may be arranged at inlet and outlet sides of the roll pressmachine 4 so as to apply low tension to the core member 1. However, thisis disadvantageous in complicated production line and increasedequipment expenses.

In view of the above, the invention was made to provide a cell electrodeplate and a process for producing the same which can, withoutcomplicating the production line, surely prevent a core member made ofmetal foil from being broken, smoothen the operation of the productionline and improve the production efficiency and reduce the equipmentexpenses.

Means or Measures for Solving the Problems

The invention is directed to a cell electrode plate comprising aband-like core member made of metal foil with a plurality of coatingsmade of electrode active material applied longitudinally of anddiscontinuously on at least one of upper and lower surfaces of the coremember, said core member being pressed by press rolls,

characterized in that at least one of opposite widthwise ends oflongitudinally discontinuous exposed portions of the core member with nocoatings is provided with pass-by transition portions for the pressrolls, said transition portions having thickness substantially same asthat of the coatings.

In the cell electrode plate, the transition portions are preferably madeof electrode active material same as that of which the coatings aremade.

In the cell electrode plate, the transition portions may be arranged tobridge the widthwise ends of the adjacent coatings together;alternatively, the transition portions may be arranged to have requiredspacing from the widthwise ends of the adjacent coatings.

In the cell electrode plate, the transition portions are preferablyarranged outwardly of the trimming lines on the opposite widthwise endsof the core member.

The invention is also directed to a process for producing a cellelectrode plate, said cell electrode plate comprising a band-like coremember made of metal foil with a plurality of coatings made of electrodeactive material applied longitudinally of and discontinuously on atleast one of upper and lower surfaces of the core member, said coremember being pressed by press rolls,

characterized in that at least one of opposite widthwise ends oflongitudinally discontinuous exposed portions of the core member with nocoatings is provided with pass-by transition portions for the pressrolls, said transition portions having thickness substantially same asthat of the coatings, the core member with the transition portions beingpressed by the press rolls to thereby produce a cell electrode plate.

In the process for producing the cell electrode plate, the transitionportions are preferably made of electrode active material same as thatof which the coatings are made.

In the process for producing the cell electrode plate, the transitionportions may be arranged to bridge widthwise ends of the adjacentcoatings together; alternatively, the transition portions may bearranged to have required spacing from the widthwise ends of theadjacent coatings.

In the process for producing the cell electrode plate, the transitionportions are preferably arranged outwardly of trimming lines on theopposite widthwise ends of the core member.

Effects of the Invention

According to a cell electrode plate and a process for producing the sameof the invention, excellent effects can be obtained such that, withoutcomplicating the production line, a core member made of metal foil canbe certainly prevented from being broken and the production line can besmoothly operated to thereby attain improved productive efficiency andreduced equipment expenses.

BRIEF DESCRIPTION OF THE DRAWINGS

[FIG. 1] A plan view showing a conventional cell electrode plate and aconventional process for producing the same.

[FIG. 2] A view looking in the direction of arrows II in FIG. 1.

[FIG. 3] A side view showing pressing of the cell electrode plate by aroll press machine.

[FIG. 4] A view looking in the direction of arrows IV in FIG. 3.

[FIG. 5] A plan view showing an embodiment of the invention.

[FIG. 6] A view looking in the direction of arrows VI in FIG. 5.

[FIG. 7] A plan view showing a further embodiment of the invention.

[FIG. 8] A view looking in the direction of arrows VIII in FIG. 7.

EXPLANATION OF THE REFERENCE NUMERALS

-   1 core member made of metal foil-   2 coatings made of electrode positive material-   3 cell electrode plate-   4 roll press machine-   5 press roll-   6 press roll-   7 discontinuous exposed portion-   8 pass-by transition portion for press roll-   L trimming line

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the invention will be disclosed in conjunction withattached drawings.

Embodiment 1

FIGS. 5 and 6 show an embodiment of the invention in which parts similarto those shown in FIGS. 1-4 are represented by the same referencenumerals. The embodiment is fundamentally similar in structure to theprior art shown in FIGS. 1-4 and resides in that, as shown in FIGS. 5and 6, opposite widthwise ends of longitudinally discontinuous exposedportions 7 on a core member 1 made of metal foil, which has no coatings2 made of electrode active material, are provided with pass-bytransition portions 8 for the press rolls, said transition portions 8having thickness substantially same as that of the coating 2.

In the embodiment, the transition portions 8 are made of electrodeactive material same as that of which the coatings 2 are made andarranged to bridge the widthwise ends of the adjacent coatings 2together. For trimming which is conducted after pressing of the cellelectrode plate 3 in such a manner that the opposite widthwise ends ofthe core member 1 are cut by predetermined size, the transition portions8 are arranged outwardly of trimming lines on the core member 1.

Next, mode of operation of the above embodiment will be described.

Where the core member 1 with the coatings 2 made of electrode activematerial and arranged longitudinally of and discontinuously on the coremember is pressed by the press rolls 5 and 6 of the roll press machine 4so as to enhance the bulk density of the electrode active material andwhen the discontinuous exposed portions 7 longitudinally on the coremember 1 with no coatings 2 are passed through the press rolls 5 and 6,the press rolls 5 and 6 crush up and run upon the transition portions 8so that, unlike the prior art, the press rolls 5 and 6 are preventedfrom falling in the discontinuous exposed portions 7 on the core member1 and attacking the core member 1 into possible breakage of the coremember 1. As a result, averted are shutdown of the production line andlowering of the productive efficiency.

Moreover, unlike the prior art, the core member 1 can be prevented frombeing broken without providing lower tension applicators at inlet andoutlet sides of the roll press machine 4 for application of lowertension on the core member 1, so that averted are complicated productionline and increased equipment expenses.

In the present embodiment, the transition portions 8 are arranged atopposite widthwise ends of the discontinuous exposed portions 7;however, they may be provided at only one of the widthwise ends of thediscontinuous exposed portions 7, which is also effective for preventionof the press rolls 5 and 6 from attacking the core member 1.

The transition portions 8 may be made of material different from thematerial of which the coatings 2 are made. However, if as in the presentembodiment they are made of electrode active material same as that ofwhich the coatings 2 are made, then the transition portions 8 may beprovided concurrently upon arrangement of the coatings 2 in the form ofapplication of the electrode active material on the core member 1, whicheliminates the necessity of providing the transition portions 8 in aseparate step.

After the cell electrode plate 3 is pressed, trimming is conductedthrough cutting the opposite widthwise ends of the core member 1 bypredetermined size; on the other hand, the discontinuous exposedportions 7 are required to be exposed for, for example, connection ofelectrode wires. In the embodiment, the transition portions 8 arearranged outwardly of trimming lines L on the opposite widthwise ends ofthe core member 1 and therefore are cut out by the trimming, so thatthere is no fear of connection of for example electrode wires to thediscontinuous exposed portions 7 being inhibited.

Thus, the core member 1 can be certainly prevented from being broken andthe production line can be smoothly operated to attain improvedproductive efficiency and reduced equipment expenses.

Embodiment 2

FIGS. 7 and 8 show a further embodiment of the invention in which partssimilar to those shown in FIGS. 5 and 6 are represented by the samereference numerals and in which pass-by transition portions 8 for pressrolls are arranged to have required spacing from the widthwise ends ofthe adjacent coatings 2.

In the embodiment, as in the embodiment shown in FIGS. 5 and 6, thetransition portions 8 are made of electrode active material same as thatof which the coatings 2 are made, and are arranged outwardly of thetrimming lines L on the opposite widthwise ends of the core member 1.Their planar shape is semicircular; however, of course, it may be ofrectangle or other polygon.

Arrangement of the transition portions 8 to have required spacing fromthe widthwise ends of the adjacent coatings 2 as shown in FIGS. 7 and 8may attain effects and advantages same as those in the embodiment shownin FIGS. 5 and 6. This is also advantageous in that the electrode activematerial required for the transition portions 8 is minimized.

It is to be understood that a cell electrode plate and a process forproducing the same according to the invention are not limited to theabove-mentioned embodiments and that various changes and modificationsmay be applied without departing from the spirit of the invention. Forexample, the invention may be applicable for both of cell positive- andnegative-pole.

INDUSTRIAL APPLICABILITY

A cell electrode plate and a process for producing the same according tothe invention may be properly applicable to for example a lithium-cellpositive pole member in which electrode mixture or positive pole activematerial such as LiCoO₂ is applied and dried on a core member orcollector made of metal foil such as aluminum or copper foil and then ispressed by a roll press machine with press rolls so at to enhance bulkdensity of the positive pole active material.

1-14. (canceled)
 15. A cell electrode plate comprising: a band-like coremember made of metal foil with a plurality of coatings made of electrodeactive material and applied longitudinally of and discontinuously on atleast one of upper and lower surfaces of the core member, said coremember being pressed by press rolls, wherein at least one of oppositewidthwise ends of longitudinally discontinuous exposed portions with nocoatings on the core member includes pass-by transition portions for thepress rolls, said transition portions having a thickness substantiallysame as that of the coatings.
 16. A cell electrode plate as claimed inclaim 15, wherein the transition portions are made of electrode activematerial same as that of which the coatings are made.
 17. A cellelectrode plate as claimed in claim 15, wherein the transition portionsare arranged to bridge widthwise ends of adjacent coatings together. 18.A cell electrode plate as claimed in claim 15, wherein the transitionportions are arranged to have a required spacing from widthwise ends ofadjacent coatings.
 19. A cell electrode plate as claimed in claim 15,wherein the transition portions are arranged outwardly of trimming lineson opposite widthwise ends of the core member.
 20. A cell electrodeplate as claimed in claim 17, wherein the transition portions arearranged outwardly of trimming lines on the opposite widthwise ends ofthe core member.
 21. A cell electrode plate as claimed in claim 18,wherein the transition portions are arranged outwardly of trimming lineson the opposite widthwise ends of the core member.
 22. A cell electrodeplate as claimed in claim 16, wherein the transition portions arearranged to bridge widthwise ends of adjacent coatings together.
 23. Acell electrode plate as claimed in claim 16, wherein the transitionportions are arranged to have a required spacing from widthwise ends ofadjacent coatings.
 24. A cell electrode plate as claimed in claim 16,wherein the transition portions are arranged outwardly of trimming lineson opposite widthwise ends of the core member.
 25. A cell electrodeplate as claimed in claim 22, wherein the transition portions arearranged outwardly of trimming lines on the opposite widthwise ends ofthe core member.
 26. A cell electrode plate as claimed in claim 23,wherein the transition portions are arranged outwardly of trimming lineson the opposite widthwise ends of the core member.
 27. A process forproducing a cell electrode plate, said cell electrode plate including aband-like core member made of metal foil with a plurality of coatingsmade of electrode active material and applied longitudinally of anddiscontinuously on at least one of upper and lower surfaces of the coremember, said core member being pressed by press rolls, wherein at leastone of opposite widthwise ends of longitudinally discontinuous exposedportions of the core member with no coatings includes pass-by transitionportions for the press rolls, said transition portions having athickness substantially same as that of the coatings, the core memberwith the transition portions being pressed by the press rolls to therebyproduce a cell electrode plate.
 28. A process for producing a cellelectrode plate as claimed in claim 27, wherein the transition portionsare made of electrode active material same as that of which the coatingsare made.
 29. A process for producing a cell electrode plate as claimedin claim 27, wherein the transition portions are arranged to bridgewidthwise ends of adjacent coatings together.
 30. A process forproducing a cell electrode plate as claimed in claim 27, wherein thetransition portions are arranged to have a required spacing from thewidthwise ends of adjacent coatings.
 31. A process for producing a cellelectrode plate as claimed in claim 27, wherein the transition portionsare arranged outwardly of trimming lines on the opposite widthwise endsof the core member.
 32. A process for producing a cell electrode plateas claimed in claim 29, wherein the transition portions are arrangedoutwardly of trimming lines on the opposite widthwise ends of the coremember.
 33. A process for producing a cell electrode plate as claimed inclaim 30, wherein the transition portions are arranged outwardly oftrimming lines on the opposite widthwise ends of the core member.
 34. Aprocess for producing a cell electrode plate as claimed in claim 28,wherein the transition portions are arranged to bridge widthwise ends ofthe adjacent coatings together.
 35. A process for producing a cellelectrode plate as claimed in claim 28, wherein the transition portionsare arranged to have a required spacing from widthwise ends of theadjacent coatings.
 36. A process for producing a cell electrode plate asclaimed in claim 28, wherein the transition portions are arrangedoutwardly of trimming lines on opposite widthwise ends of the coremember.
 37. A process for producing a cell electrode plate as claimed inclaim 34, wherein the transition portions are arranged outwardly oftrimming lines on the opposite widthwise ends of the core member.
 38. Aprocess for producing a cell electrode plate as claimed in claim 35,wherein the transition portions are arranged outwardly of trimming lineson the opposite widthwise ends of the core member.